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(Color) Schematic cross section of a tunneling structure. (b) Top view of a device with four wires attached. (c) TEM micrograph showing the thin GaAs barrier (cleaned by ) before preparation of the second Fe contact. (d) High-resolution TEM micrographs, of an ideal interface and (e) of an interface after treatment.
(Color online) (a) Normalized TMR traces of a tunnel junction with thick barrier at and at room temperature. Bias voltage: . Both interfaces were cleaned with before deposition of iron. (b) dependence of the spin polarization derived from Jullière’s model for the interface combinations: hy-hy, ox-hy, and ox-ox. Bias voltage: .
(Color) Bias dependence of the TMR for junctions with one “ideal” epitaxial interface. The other interface was either untreated (open squares) or cleaned by a plasma (triangles). is applied along the easy  direction. Two insets show examples for positive and negative TMR at and , respectively. The right inset displays the circuitry; the lower interface is the epitaxial one. Also shown is the calculated spin polarization for the Fe layer closest to the barrier. For energies above minority spins dominate the interfacial density of states.
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